The most thing during detection procedure of crystalline silicon product process, for instance, solar panel process, is that rapidly and correctly detecting and excluding products having fragmentation defects, so as to maintain defective rate and reliability of products. Since the fragmentation defects are classified as naked-eyes-identifiable external fragmentation defects and naked-eyes-unidentifiable internal fragmentation defects, the detection procedure is generally focused on how to immediately detect products having internal fragmentation defects.
As disclosed in Taiwan Patent Issuance No. M350015, a device for inspecting defect of photovoltaic element is used to find out a fragmentation defect of a photovoltaic element, for instance a solar panel, through analyzing a spectrum of an acoustic signal in frequency domain excited from the photovoltaic element. The device enables the fragmentation defect of the photovoltaic element to excite the acoustic signal through a resonance manner; however, it is not easy to excite an internal fragmentation defect, which cannot be identified by naked eyes, and generate an acoustic signal through a resonance mode. Hence, in practice, such detection device is usually unable to find out whether or not a solar panel has an internal fragmentation defect. Furthermore, the detection device have to equipped with a database pre-storing a spectrum of a standard acoustic signal to perform subsequent analysis and inspection, so as to cause extra cost burden to an user. Moreover, the accuracy of an analysis result obtained by only analyzing the spectrum of the acoustic signal in frequency domain is often insufficiently low, and thus the result cannot efficiently identify a solar panel having external or internal fragmentation defects.
Additionally, an inspection technique is disclosed in U.S. Patents Publication No. 20050097961 A1 and 20060062403 A1. Specifically, an acoustic signal generated from a tested substrate, for instance, a solar panel, is analyzed in frequency domain, so as to identify a fragmentation defect of the solar panel by a spectrum of the acoustic signal in frequency domain. Nevertheless, since the above inspection technique enables the tested substrate to excite the acoustic signal through directly striking the tested substrate, damages following with improper operation would be contributed to the tested substrate. Furthermore, such inspection technique also has to be cooperated with a database pre-storing the spectrum of a standard acoustic signal, and thus will cause the extra burden to the user. In addition, the aforementioned inspection technique also only analyzes the spectrum of the acoustic signal in frequency domain, and thus cannot provide an analysis result with higher accuracy.
U.S. Pat. No. 4,603,584 discloses an inspection technique which is still limited to analyzes a spectrum of an acoustic signal in frequency domain. Hence, it still couldn't provide an analysis result with higher accuracy.
In this regard, there is a need to develop a defect detection system and method for detecting a crystalline product that can accurately detect not only naked-eyes-identifiable external fragmentation defects but also naked-eyes-unidentifiable internal fragmentation defects while neither contributing any improper damage to the tested crystalline product nor increasing user load.